Human intelligence is one of the most important inventions of evolution. This is the result of a sprint that began millions of years ago and led to an increase in brains and the emergence of new abilities. Ultimately, humans straightened their backs, took a plow and created civilization, while our primate cousins remained in the trees. So, scientists from southern China reported that they tried to close the evolutionary gap by creating several transgenic macaques with additional copies of a human gene, presumably playing a role in the formation of human intelligence.
And no, they were not afraid to do it even after the situation with genetically modified twins.
What happens if you cross a monkey and a human?
“This was the first attempt to understand the evolution of human consciousness using the transgenic monkey model,” says Bing Su, the geneticist at the Kunming Institute of Zoology who led the work.
According to the findings, the modified monkeys performed better on memory tests involving color cards and bricks, and their brains took longer to develop, like in human children. There were no differences in brain size. However, these experiments are not enough to reveal the secrets of the human mind or give birth to the "planet of the apes".
In contrast, several Western scientists called the experiments reckless and said they doubted the ethics of creating genetically modified primates given China's technological advantage in this area.
“Using transgenic monkeys to study human genes associated with brain evolution is very risky,” says James Sikela, a geneticist who conducts comparative research on primates at the University of Colorado. He is concerned that the experiment demonstrates a disdain for animals and will soon lead to more extreme modifications. “This is a classic slippery slope question, and the more research is done in this direction, the more acute the question will be,” he says.
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While researching primates in Europe and the United States is becoming increasingly difficult, China is quite successful and hastily applying the latest DNA tools to animals. This country was the first to create monkeys modified with CRISPR, and in January a Chinese institute announced that it had created half a dozen clones of severely mentally impaired monkeys.
"It is troubling to develop this area in this way," says Sikela.
Evolution history
Su, a researcher at the Kunming Institute of Zoology, specializes in looking for signs of "Darwinian selection" - that is, genes that proliferate because of their success. His search covered topics such as the adaptation of Himalayan yaks to high altitude and the evolution of human skin color in response to cold winters.
However, the biggest mystery of all is the mind. We know that the brains of our human ancestors grew rapidly in size and power. To find the genes that caused the change, scientists looked for differences between humans and chimpanzees, whose genes are about 98% similar to ours. The goal, Sikela said, was to find “the jewels of our genome,” that is, the DNA that makes us unique.
For example, one popular candidate gene called FOXP2 - the "language gene" - has become known for its potential association with human speech. One of the English families whose members inherited an abnormal version of this gene developed speech problems. Scientists from Tokyo and Berlin very soon derived this mutant gene in mice and listened with ultrasonic microphones to see if their squeaks changed.
Su was fascinated by another gene: MCPH1, or microcephalin. Not only did the sequence of this gene differ from humans to monkeys, babies with microcephalin damage are born with tiny heads, meaning there is a connection to the brain. Together with his students, Su used calipers and wrenches to measure the heads of 867 Chinese men and women and see if the results could be explained by differences in the gene.
By 2010, though, Su saw a chance to conduct a potentially more accurate experiment: adding a human microcephalin gene to a monkey. By then, China had begun to apply the latest genetic tools to its large monkey broods, making the country a Mecca for foreign scientists looking for monkeys to experiment with.
To create the altered animals, Su and staff at the Yunnan Primate Biomedical Research Laboratory exposed monkey embryos to a virus containing a human version of microcephalin. It turned out 11 monkeys, 5 of which survived and provided brains for measurements. Each of these monkeys had two to nine copies of a human gene in their bodies.
Monkeys Soo have raised a number of unusual questions about animal rights. In 2010, Sikela and three colleagues wrote an article, "The Ethics of Using Non-Human Transgenic Primates to Study What Makes Us Human," which concluded that genes in the human brain should never be implanted in apes like chimpanzees because they are too much like us. Where will they live and what will they do? You shouldn't create a creature that won't get a normal life in any context."
In an email message, Su says he agrees that monkeys are so close to humans that their brains should not be altered. But the last common ancestor between apes and humans was 25 million years ago. For Su, that's an argument. “While their genome is close to ours, there are also tens of millions of differences,” he says. He does not think that monkeys will become anything more than monkeys. "You can't do that by introducing multiple human genes."
Smart monkeys
Judging from their experiments, the Chinese team really expected their transgenic monkeys to get improved intelligence and larger brains. That's why they put the creatures in MRI machines to measure white matter and put them through computerized memory tests. According to their report, the transgenic monkeys did not have an enlarged brain, but they performed better on a short memory test, and the team noted this.
Some scientists believe that the Chinese experiment did not provide any new information. Among them is Martin Steiner, a computer scientist at the University of North Carolina and an MRI specialist. He notes that there were several aspects of this study that would prevent it from being carried out in the United States. Questions have also been raised about whether the animals were properly cared for.
And after what he saw, Steiner says he does not expect further research into the evolution of transgenic apes. “I don’t think this is a good direction,” he says. “We have created this animal that is different from others. When we conduct experiments, we should be perfectly aware that we are trying to understand why, that we are helping society - but this is not the case. " One problem is that genetically modified monkeys are expensive to create and maintain. With just five modified monkeys, it's difficult to come to clear conclusions about whether they really differ from regular monkeys in terms of brain size or memory skills. “They're trying to understand brain development. And I don't think they will succeed."
Su himself says it's too early to talk about results. What do you think?
Ilya Khel
